The present invention relates to connecting elements used in the making of a structure for the fluid-tight connection between the side wall and the roof of a storage tank in particular for a molten salt.
There are already known heat-insulated storage tanks in particular for molten salts with a corrugated vertical cylindrical side wall formed with two orthogonally intersecting sets of parallel, respectively straight vertical and circular horizontal corrugations and with a generally flat circular roof suspended within the cylindrical enclosure with a radial play or clearance to proivde for its free thermal expansion.
In the particular case of storage of a molten salt which is at a temperature of 570.degree. C. (eutectic mixture of potassium and sodium salts) the latter has a tendency to rise and to flow over the roof thereby polluting the for instance fibrous insulation covering the outer face or top side of the roof thus impairing its insulating properties.
Moreover the air is heated up through contact with the molten salt and is thus brought to a temperture which is nearly that of the salt so that that air owing to the convection phenomenon is likely to heat dangerously up the upper structure or dome from which the roof is suspended and which being made from carbon steel should not exceed a given temperature.